1. Field of the Invention
This invention pertains to aromatic polyesters capable of forming optically anisotropic melts, and to high strength/high modulus filaments, tough films and moldings thereof.
2. Description of the Prior Art
A class of aromatic polyesters that form optically anisotropic melts from which oriented filaments can be melt-spun has been described in Schaefgen U.S. Pat. No. 4,118,372. One polyester disclosed therein is poly(chloro-1,4-phenylene terephthalate/4,4'-bibenzoate) (70/30). Filaments are melt-spun from the polymer and then heat treated to increase tenacity.
Calundann U.S. Pat. No. 4,256,624 discloses a melt-processable aromatic polyester that is formed from moieties derived from para-oriented dihydric phenol, para-oriented aromatic dicarboxylic acid and 6-hydroxy-2-naphthoic acid. The moiety derived from 4,4'-dihydroxybiphenyl is taught therein as a suitable symmetrical dioxy aryl moiety. Cottis U.S. Pat. No. 3,975,487 discloses aromatic polyesters from hydroxybenzoic acid, 4,4'-dihydroxybiphenyl, terephthalic and isophthalic acids.
Kuhfuss, et al. U.S. Pat. No. 3,778,410, Col. 5, discloses p(p'-acetoxyphenyl)benzoic acid as a starting material in preparation of copolyesters.